Allow sending multiple responses for GroupMe

[josephfrazier]

[simalexan]

Hey, this contribution is great! It's very appreciated and thank you for implementing it. We've looked into the code and would only suggest instead of the added dependency for promiseEach, maybe implement it using a similar solution mentioned here https://stackoverflow.com/questions/37916064/sequential-iteration-using-es6-promises

Because Lambda uploads take longer with more dependencies, we tend to keep as few as possible. What do you think?

[josephfrazier]

Thanks for the quick feedback! I copied the promise-each implementation into lib/promise-each.js, modified it to remove dependencies and linting errors, and used it instead. What do you think?

[josephfrazier]

Hey @simalexan, have you had a chance to review the most recent changes? I just stumbled across this again and thought I'd check in.